Projecting exposure method

ABSTRACT

A spatial light modulating method performs spatial light modulation of light produced by a light source. The method includes forming an image of a two-dimensional pattern of the light, which has been obtained from the spatial light modulation, on a photosensitive material, using an image-sided telecentric optical system. The method further includes altering an axial air separation, upstream of the photosensitive material, to thereby adjust a focusing point at the time of the formation of the image of the two-dimensional pattern of the light.

This is a Continuation of application Ser. No. 10/839,228 filed May 6,2004 which is now U.S. Pat. No. 6,930,761.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a projecting exposure apparatus. Thisinvention particularly relates to a projecting exposure apparatus,wherein an image of a two-dimensional pattern of light having beenobtained from spatial light modulation is projected through animage-side telecentric image forming optical system onto aphotosensitive material, and the photosensitive material is thus exposedto the two-dimensional pattern of the light.

2. Description of the Related Art

Projecting exposure apparatuses, wherein spatial light modulation meansfor performing spatial light modulation of incident light is utilized, atwo-dimensional pattern of the light, which has been obtained from thespatial light modulation performed by the spatial light modulationmeans, is projected onto a photosensitive material, and thephotosensitive material is thus exposed to the two-dimensional patternof the light, have heretofore been known. Also, projecting exposureapparatuses, wherein a digital micromirror device (hereinbelow referredto as the DMD) comprising a plurality of (e.g., 1,024×756) micromirrors,which allow alteration of their inclination angles and which are arrayedin a two-dimensional pattern, is utilized as the spatial lightmodulation means, have heretofore been known. (The projecting exposureapparatuses, wherein the digital micromirror device (DMD) is utilized asthe spatial light modulation means, are described in, for example,Patent Literature 1.) As the digital micromirror device (DMD), forexample, a DMD supplied by Texas Instruments Co. has been known.Projectors for dynamic images, wherein the DMD is utilized, and thelike, have been used in practice.

The projecting exposure apparatuses utilizing the DMD are provided withan image forming lens for forming an image of each of the micromirrorsof the DMD on the photosensitive material. With the projecting exposureapparatuses utilizing the DMD, the images of only the light, which hasbeen reflected from certain micromirrors inclined at predeterminedangles among the micromirrors that receive the irradiated light forexposure, and which travels toward the image forming lens, are formedthrough the image forming lens and on the photosensitive material. Inthis manner, the two-dimensional pattern having been obtained from thespatial light modulation performed by the DMD is projected onto thephotosensitive material, and the photosensitive material is thus exposedto the two-dimensional pattern. Specifically, with the projectingexposure apparatuses utilizing the DMD, the exposure operation isperformed such that each of pixels constituting the image of thetwo-dimensional pattern projected onto the photosensitive materialcorresponds to one of the micromirrors.

Also, attempts have heretofore been made to expose a photosensitivematerial, for example, a board on which a photoresist has been overlaid,to light carrying a circuit pattern by use of the projecting exposureapparatuses described above. Further, it has been considered to employ atechnique, wherein an image forming optical system, which is telecentricon the image side, is utilized as the image forming optical system ofthe projecting exposure apparatuses, such that the image of the circuitpattern is capable of being formed on the board with accuratemagnification, i.e. with quality free from variation in size of theimage of the circuit pattern and distortion of the image.

[Patent Literature 1]

-   -   Japanese Unexamined Patent Publication No. 2001-305663

However, at the time of the exposure operation for the circuit patterndescribed above, it is necessary to perform an adjustment of a focusingpoint such that the position of the formation of the image of thecircuit pattern performed by the image forming optical system and theposition of the photoresist layer overlaid on the board may coincidewith each other. It may be considered that the adjustment of thefocusing point be performed with, for example, an adjustment of an axialair separation between the lenses constituting the image forming opticalsystem. However, it is not always possible to alter the axial airseparation between the lenses constituting the image forming opticalsystem such that the size of the image of the circuit pattern may notvary and such that the image of the circuit pattern may not bedistorted. Therefore, it is desired that the adjustment of the focusingpoint is capable of being performed with an adjustment of the separationbetween the image forming optical system and the board provided with thephotoresist layer.

However, for example, in cases where the exposure operation is to beperformed for a base plate for the formation of a liquid crystal displaypanel, a base plate for the formation of a plasma display panel, or thelike, which base plate has a comparatively large size, the size of theimage forming optical system, or the like, becomes large as the size ofthe base plate subjected to the exposure operation becomes large, andthe problems occur in that it is not always possible to alter theseparation between the image forming optical system and the base platein order to perform the adjustment of the focusing point. Also, forexample, in cases where subregions of the entire region of the baseplate are to be subjected successively to the exposure operation, whilethe base plate is being conveyed, and the exposure operation is thusperformed for the entire exposure region, it is required that a shift infocusing point, which shift occurs due to warpage of the shape of thebase plate (e.g., the warpage of the shape of 100 μm), or the like, becompensated for quickly in each of steps of the conveyance of the baseplate. Therefore, the problems occur in that it is not always possibleto alter the separation between the image forming optical system and thebase plate in order to perform the adjustment of the focusing point.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a projectingexposure apparatus, wherein projection of a two-dimensional pattern oflight, which has been obtained from spatial light modulation, is capableof being performed such that an adjustment of a focusing point iscapable of being performed easily and quickly.

The present invention provides a first projecting exposure apparatus,comprising:

i) spatial light modulation means for performing spatial lightmodulation of light, which has been produced by a light source, andthereby forming a two-dimensional pattern of the light, and

ii) an image-side telecentric image forming optical system for formingan image of the two-dimensional pattern of the light, which has beenobtained from the spatial light modulation performed by the spatiallight modulation means, on a photosensitive material,

the two-dimensional pattern of the light being projected onto thephotosensitive material, the photosensitive material being thus exposedto the two-dimensional pattern of the light,

wherein the projecting exposure apparatus further comprises axial airseparation adjusting means, which is located between the image formingoptical system and the photosensitive material, and which alters anaxial air separation between the image forming optical system and thephotosensitive material and thereby adjusts a focusing point at the timeof the formation of the image of the two-dimensional pattern of thelight.

The present invention also provides a second projecting exposureapparatus, comprising:

i) spatial light modulation means provided with a plurality of pixelsections arrayed in two-dimensional directions, which pixel sectionsmodulate incident light in accordance with a predetermined controlsignal, the spatial light modulation means performing spatial lightmodulation of the light with the plurality of the pixel sections,

ii) a first image forming optical system for forming an image of atwo-dimensional pattern of the light, which has been obtained from thespatial light modulation performed by the spatial light modulationmeans,

iii) a microlens array located in the vicinity of a plane of imageformation of the two-dimensional pattern, whose image is formed by thefirst image forming optical system, the microlens array being providedwith a plurality of microlenses arrayed in two-dimensional directions,each of which microlenses transmits one of light beams correspondingrespectively to the pixel sections of the spatial light modulation meansand having passed through the first image forming optical system, and

iv) a second image forming optical system, which is an image-sidetelecentric image forming optical system, the second image formingoptical system forming an image of each of the light beams, which havepassed through the microlens array, on a photosensitive material,

the two-dimensional pattern of the light being projected onto thephotosensitive material, the photosensitive material being thus exposedto the two-dimensional pattern of the light,

wherein the projecting exposure apparatus further comprises axial airseparation adjusting means, which is located between the second imageforming optical system and the photosensitive material, and which altersan axial air separation between the second image forming optical systemand the photosensitive material and thereby adjusts a focusing point atthe time of the formation of the image of the two-dimensional pattern ofthe light.

The present invention further provides a third projecting exposureapparatus, comprising:

i) spatial light modulation means provided with a plurality of pixelsections arrayed in two-dimensional directions, which pixel sectionsmodulate incident light in accordance with a predetermined controlsignal, the spatial light modulation means performing spatial lightmodulation of the light with the plurality of the pixel sections,

ii) a first image forming optical system for forming an image of atwo-dimensional pattern of the light, which has been obtained from thespatial light modulation performed by the spatial light modulationmeans,

iii) a microlens array located in the vicinity of a plane of imageformation of the two-dimensional pattern, whose image is formed by thefirst image forming optical system, the microlens array being providedwith a plurality of microlenses arrayed in two-dimensional directions,each of which microlenses transmits one of light beams correspondingrespectively to the pixel sections of the spatial light modulation meansand having passed through the first image forming optical system, and

iv) a second image forming optical system, which is an image-sidetelecentric image forming optical system, the second image formingoptical system forming an image of each of the light beams, which havepassed through the microlens array, on a photosensitive material,

the two-dimensional pattern of the light being projected onto thephotosensitive material, the photosensitive material being thus exposedto the two-dimensional pattern of the light,

wherein the projecting exposure apparatus further comprises axial airseparation adjusting means, which is located between the microlens arrayand the second image forming optical system, and which alters an axialair separation between the microlens array and the second image formingoptical system and thereby adjusts a focusing point at the time of theformation of the image of the two-dimensional pattern of the light.

Each of the first, second, and third projecting exposure apparatuses inaccordance with the present invention may be modified such that theaxial air separation adjusting means is provided with a wedge-shapedprism pair and adjusts the focusing point by moving a position of one ofwedge-shaped prisms, which constitute the wedge-shaped prism pair, withrespect to the position of the other wedge-shaped prism and in adirection, which is associated with a minimum width of each of regionsof the formation of the image of the two-dimensional pattern on thephotosensitive material.

Also, each of the first, second, and third projecting exposureapparatuses in accordance with the present invention may be modifiedsuch that the spatial light modulation means is a digital micromirrordevice.

Alternatively, the spatial light modulation means may be a maskcomprising a glass plate, on which a two-dimensional pattern has beendrawn, or the like.

Further, each of the first, second, and third projecting exposureapparatuses in accordance with the present invention may be modifiedsuch that the digital micromirror device performs the spatial lightmodulation by use of only a part of the plurality of the pixel sections,which constitute the digital micromirror device and are arrayed in thetwo-dimensional directions.

The term “image-side telecentric image forming optical system” as usedherein means the image forming optical system, which forms optical pathsthat are telecentric on the image side.

The two-dimensional pattern of the light may represent an image to bedisplayed. Alternatively, the two-dimensional pattern of the light mayrepresent an electric wiring circuit pattern, or the like.

By way of example, the wedge-shaped prism pair may be constituted of apair of the wedge-shaped prisms obtained with a process wherein atransparent plane-parallel plate is cut along an oblique plane, which isinclined with respect to parallel planes of the transparentplane-parallel plate. In such cases, the wedge-shaped prism pair arecapable of forming a plane-parallel plate with the combination of twowedge-shaped prisms. Therefore, the position of one of the twowedge-shaped prisms may be moved with respect to the other wedge-shapedprism and in one direction, and the thickness of the plane-parallelplate, which is formed with the combination of the one pair of thewedge-shaped prisms, is thus capable of being altered. With thealteration of the thickness of the plane-parallel plate, which is formedwith the combination of the one pair of the wedge-shaped prisms, theaxial air separation between the image forming optical system and thephotosensitive material is capable of being altered.

The photosensitive material may be a board for the formation of aprinted circuit board, which board is coated with a photoresist forforming a two-dimensional circuit pattern. Alternatively, thephotosensitive material may be a base plate for the formation of aliquid crystal display panel or a plasma display panel, which base plateis coated with a photoresist for forming a two-dimensional circuitpattern.

As will be understood from the specification, it should be noted thatthe term “moving a position of one of wedge-shaped prisms with respectto the position of the other wedge-shaped prism” as used herein meansmovement of the position of the one wedge-shaped prism relative to theposition of the other wedge-shaped prism, and embraces the cases whereinthe position of the one wedge-shaped prism is moved while the otherwedge-shaped prism is kept stationary, the cases wherein the position ofthe other wedge-shaped prism is moved while the one wedge-shaped prismis kept stationary, and the cases wherein both the position of the onewedge-shaped prism and the position of the other wedge-shaped prism aremoved.

The first projecting exposure apparatus in accordance with the presentinvention is provided with the axial air separation adjusting means,which alters the axial air separation between the image forming opticalsystem and the photosensitive material and thereby adjusts the focusingpoint at the time of the formation of the image of the two-dimensionalpattern of the light. Therefore, with the first projecting exposureapparatus in accordance with the present invention, the adjustment ofthe focusing point by the alteration of the axial air separation betweenthe image forming optical system and the photosensitive material iscapable of being performed easily and quickly. Specifically, the axialair separation adjusting functions of the axial air separation adjustingmeans are capable of being separated from the image forming functions ofthe image forming optical system, the functions for supporting andconveying the photosensitive material, and the like. Therefore, theconstitution for the adjustment of the axial air separation is capableof being kept simpler than with a conventional technique, and theadjustment of the focusing point at the time of the projection of thetwo-dimensional pattern of the light onto the photosensitive material iscapable of being performed easily and quickly.

Each of the second and third projecting exposure apparatuses inaccordance with the present invention comprises the first image formingoptical system for forming the image of the two-dimensional pattern ofthe light, which has been obtained from the spatial light modulationperformed by the spatial light modulation means, the microlens arraylocated in the vicinity of the plane of image formation of thetwo-dimensional pattern, whose image is formed by the first imageforming optical system, and the second image forming optical system,which is the image-side telecentric image forming optical system, thesecond image forming optical system forming the image of each of thelight beams, which have passed through the microlens array, on thephotosensitive material. Also, each of the second and third projectingexposure apparatuses in accordance with the present invention comprisesthe axial air separation adjusting means, which is located between thesecond image forming optical system and the photosensitive material, orwhich is located between the microlens array and the second imageforming optical system. Therefore, with each of the second and thirdprojecting exposure apparatuses in accordance with the presentinvention, the adjustment of the focusing point of each of the lightbeams, whose images are formed on the photosensitive material, iscapable of being performed easily and quickly. Specifically, the axialair separation adjusting functions of the axial air separation adjustingmeans are capable of being separated from the image forming functions ofthe first image forming optical system, the image forming functions ofthe second image forming optical system, the functions for supportingand conveying the photosensitive material, and the like. Therefore, theconstitution for the adjustment of the axial air separation is capableof being kept simpler than with a conventional technique, and theadjustment of the focusing point at the time of the projection of thetwo-dimensional pattern of the light onto the photosensitive material iscapable of being performed easily and quickly.

Each of the first, second, and third projecting exposure apparatuses inaccordance with the present invention may be modified such that theaxial air separation adjusting means is provided with the wedge-shapedprism pair and adjusts the focusing point by moving the position of oneof the wedge-shaped prisms, which constitute the wedge-shaped prismpair, with respect to the position of the other wedge-shaped prism andin the direction, which is associated with the minimum width of each ofthe regions of the formation of the image of the two-dimensional patternon the photosensitive material. With the modification described above,the distance of the movement of the wedge-shaped prism at the time ofthe adjustment of the focusing point is capable of being kept short, andthe constitution for the adjustment of the axial air separation iscapable of being kept simple.

Also, each of the first, second, and third projecting exposureapparatuses in accordance with the present invention may be modifiedsuch that the spatial light modulation means is the digital micromirrordevice, the digital micromirror device performs the spatial lightmodulation by use of only a part of the plurality of the pixel sections,which constitute the digital micromirror device and are arrayed in thetwo-dimensional directions. With the modification described above, thedistance of the movement of the wedge-shaped prism at the time of theadjustment of the focusing point is capable of being reduced evenfurther, and the adjustment of the axial air separation is capable ofbeing performed more quickly and more easily.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a developed conceptual view showing an exposure head in anembodiment of the projecting exposure apparatus in accordance with thepresent invention,

FIG. 2 is a side view showing a constitution of the exposure head alongoptical paths of light beams traveling through the exposure head,

FIG. 3 is a perspective view showing a DMD,

FIG. 4 is a side view showing an axial air separation adjusting section,

FIG. 5 is a perspective view showing a wedge-shaped prism pair,

FIG. 6 is a perspective view showing an appearance of the embodiment ofthe projecting exposure apparatus in accordance with the presentinvention,

FIG. 7 is a perspective view showing how an exposure operation isperformed by the projecting exposure apparatus of FIG. 6,

FIG. 8A is a plan view showing exposure-processed regions, which areformed on a photosensitive material,

FIG. 8B is an explanatory view showing an array of exposure processingareas, each of which is subjected to exposure processing performed byone of exposure heads,

FIG. 9 is a plan view showing a laser beam combining light source,

FIG. 10 is a side view showing the laser beam combining light source,

FIG. 11 is a front view showing the laser beam combining light source,

FIG. 12 is an enlarged plan view showing optical elements of the laserbeam combining light source,

FIG. 13A is a perspective view showing a light source unit,

FIG. 13B is an enlarged view showing a part of a laser beam radiatingsection,

FIG. 13C is a front view showing an example of an array of opticalfibers at the laser beam radiating section,

FIG. 13D is a front view showing a different example of an array ofoptical fibers at the laser beam radiating section,

FIG. 14 is a view showing how a multimode optical fiber of the laserbeam combining light source and the optical fiber at the laser beamradiating section are connected to each other,

FIG. 15A is a plan view showing how the photosensitive material isexposed to light beams in cases where the DMD is located in anorientation, which is not oblique,

FIG. 15B is a plan view showing how the photosensitive material isexposed to the light beams in cases where the DMD is located in anoblique orientation,

FIG. 16A is an explanatory view showing an example of a used region inthe DMD,

FIG. 16B is an explanatory view showing a different example of a usedregion in the DMD, and

FIG. 17 is a side view showing a different embodiment of the projectingexposure apparatus in accordance with the present invention, wherein anaxial air separation adjusting section is located between a microlensarray and a second image forming optical system, which is an image-sidetelecentric image forming optical system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will hereinbelow be described in further detailwith reference to the accompanying drawings.

FIG. 1 is a developed conceptual view showing an exposure head of anembodiment of the projecting exposure apparatus in accordance with thepresent invention. FIG. 2 is a side view showing a constitution of theexposure head along optical paths of light beams traveling through theexposure head. FIG. 3 is a perspective view showing a DMD.

The embodiment of the projecting exposure apparatus in accordance withthe present invention comprises a DMD 80 constituted of a plurality ofmicromirrors 81, 81, . . . , which are arrayed in two-dimensionaldirections. Each of the micromirrors 81, 81, . . . acts as one of thepixel sections for modulating incident light, which has been produced bya light source unit 60 acting as the light source and has then passedthrough a DMD irradiation optical system 70, in accordance with apredetermined control signal. The DMD 80 acts as the spatial lightmodulation means for performing spatial light modulation of the lightwith the micromirrors 81, 81, . . . The projecting exposure apparatusalso comprises an optical system 50 provided with a second image formingoptical system 52, which is an image-side telecentric image formingoptical system. The optical system 50 forms an image of atwo-dimensional pattern of the light, which has been obtained from thespatial light modulation performed by the DMD 80, on a photosensitivematerial 150. The projecting exposure apparatus further comprises anaxial air separation adjusting section 54, which is located between thesecond image forming optical system 52 of the optical system 50 and thephotosensitive material 150. The axial air separation adjusting section54 is provided with a wedge-shaped prism pair 540 for altering an axialair separation between the second image forming optical system 52 andthe photosensitive material 150 and thereby adjusting a focusing pointat the time of the formation of the image of the two-dimensional patternof the light. With the projecting exposure apparatus, thetwo-dimensional pattern of the light is projected onto thephotosensitive material 150, and the photosensitive material 150 is thusexposed to the two-dimensional pattern of the light.

The light source unit 60, the DMD irradiation optical system 70, the DMD80, the optical system 50 provided with the second image forming opticalsystem 52, the axial air separation adjusting section 54, and the like,are optical elements constituting an exposure head 166, which will bedescribed later. By way of example, the two-dimensional pattern mayrepresent a circuit pattern. The exposure surface of the photosensitivematerial 150 may have a size of, for example, 500 mm×600 mm. Thephotosensitive material 150 may be a board for the formation of aprinted circuit board, which board is coated with a photoresist forforming a two-dimensional circuit pattern. Alternatively, thephotosensitive material 150 may be a base plate for the formation of aliquid crystal display panel or a plasma display panel, which base plateis coated with a photoresist for forming a two-dimensional circuitpattern.

The optical system 50 provided with the second image forming opticalsystem 52, which is the image-side telecentric image forming opticalsystem, and the like, will be described hereinbelow.

Optical System 50

As illustrated in FIG. 2, an optical system 50, which is one of theoptical elements constituting the exposure head 166, comprises a firstimage forming optical system 51 for forming an image of thetwo-dimensional pattern of the light, which has been obtained from thespatial light modulation. The optical system 50 also comprises thesecond image forming optical system 52, which is the image-sidetelecentric image forming optical system. The second image formingoptical system 52 relays the image of the two-dimensional pattern, whichimage has been formed by the first image forming optical system 51, andforms the image of the two-dimensional pattern on the photosensitivematerial 150. The optical system 50 further comprises a microlens array55, an aperture array 59, and the like, which are located between thefirst image forming optical system 51 and the second image formingoptical system 52.

The microlens array 55 is constituted of a plurality of microlenses 55a, 55 a, . . . , which are arrayed in two-dimensional directions. Eachof the microlenses 55 a, 55 a, . . . is located at a positioncorresponding to one of the micromirrors 81, 81, . . . of the DMD 80(illustrated in FIG. 3), such that the microlens 55 a transmits thelight beam having been reflected from the corresponding micromirror 81of the DMD 80 and having then passed through the first image formingoptical system 51.

Also, the aperture array 59 comprises a plurality of apertures 59 a, 59a, . . . Each of the apertures 59 a, 59 a, . . . is located at aposition corresponding to one of the microlenses 55 a, 55 a, . . . ofthe microlens array 55, such that the aperture 59 a allows the passageof the light beam, which has passed through the corresponding microlens55 a of the microlens array 55.

In the optical system 50 having the constitution described above, theimage of the micromirrors 81, 81, . . . which image is formed with thelight beams having been reflected from the micromirrors 81, 81, . . . ofthe DMD 80, is enlarged by the first image forming optical system 51 toa size three times as large as the size of the original image. Each oflight beams La, La, . . . corresponding respectively to the micromirrors81, 81, . . . , which light beam has passed through the first imageforming optical system 51 after being reflected from the correspondingmicromirror 81, is collected by the corresponding microlens 55 a of themicrolens array 55, which is located in the vicinity of the position ofimage formation with the first image forming optical system 51. Each ofthe light beams La, La, . . . , which light beam has thus been collectedby the corresponding microlens 55 a, passes through the correspondingaperture 59 a. The size of the image of the micromirrors 81, 81, . . . ,which image has been formed through the microlens array 55 and theaperture array 59, is enlarged even further by the second image formingoptical system 52 by a factor of 1.67. The image of the micromirrors 81,81, . . . , which image has the thus enlarged size, passes through thewedge-shaped prism pair 540 of the axial air separation adjustingsection 54 and is formed on the photosensitive material 150. As aresult, the image of the micromirrors 81, 81, . . . of the DMD 80 isultimately enlarged by a factor of 5 (=3×1.67) and projected onto thephotosensitive material 150.

Specifically, the light beams La, La, . . . corresponding respectivelyto the micromirrors 81, 81, . . . become image-side telecentric lightbeams Lb, Lb, . . . after passing through the second image formingoptical system 52. By the adjustment of the axial air separationperformed with the axial air separation adjusting section 54, each ofthe light beams Lb, Lb, . . . is adjusted such that the focusing pointaccurately coincides with the position on the photosensitive material150. The light beams Lb, Lb, . . . are thus projected onto thephotosensitive material 150.

In cases where each of pixels constituting the image of thetwo-dimensional pattern, i.e. each of the light beams La, La, . . . ,which have passed through the first image forming optical system 51 andthe corresponding microlenses 55 a, 55 a, . . . after being reflectedfrom the corresponding micromirrors 81, 81, . . . , undergoes thickeningdue to aberrations of the optical elements described above, and thelike, the light beam La is capable of being shaped by the correspondingaperture 59 a such that the spot size of the light beam La, whichcorresponds to one of the micromirrors 81, 81, . . . and the image ofwhich is formed by the first image forming optical system 51, becomesidentical with a predetermined size. Also, as described above, each ofthe light beams La, La, . . . , which light beam has been reflected fromone of the micromirrors 81, 81, . . . is passed through the aperture 59a, which corresponds to the micromirror 81. Therefore, cross talkbetween the micromirrors 81, 81, . . . (the pixels) is capable of beingprevented from occurring, and the extinction ratio in on-off operationsof each of the micromirrors 81, 81, . . . at the time of the exposureoperation is capable of being enhanced.

The state, in which each of the micromirrors 81, 81, . . . is inclinedat the predetermined angle such that the light beam having beenreflected from the micromirror 81 travels toward the first image formingoptical system 51 of the optical system 50, is the on state of themicromirror 81. Also, the state, in which each of the micromirrors 81,81, . . . is inclined at an angle different from the predetermined anglesuch that the light beam having been reflected from the micromirror 81travels along a direction shifted from the direction of the optical pathheading toward the first image forming optical system 51 of the opticalsystem 50, is the off state of the micromirror 81. The image of thelight beam, which has been reflected from the micromirror 81 in the onstate, is formed on the photosensitive material 150, and thephotosensitive material 150 is thus exposed to the light beam.Specifically, each of the micromirrors 81, 81, . . . modulates theincident light in accordance with the alteration of the angle ofinclination of the micromirror 81. Also, the DMD 80 alters the angle ofinclination of each of the micromirrors 81, 81, . . . in accordance witha predetermined control signal and thereby performs the spatial lightmodulation of the incident light.

The axial air separation adjusting section 54 will hereinbelow bedescribed in detail with reference to FIG. 4 and FIG. 5. FIG. 4 is aside view showing an axial air separation adjusting section. FIG. 5 is aperspective view showing a wedge-shaped prism pair.

Axial Air Separation Adjusting Section 54

The axial air separation adjusting section 54 comprises a wedge-shapedprism 540A and a wedge-shaped prism 540B, which constitute thewedge-shaped prism pair 540. The axial air separation adjusting section54 also comprises a base prism holder 541A for supporting thewedge-shaped prism 540A. The axial air separation adjusting section 54further comprises slide bases 542A, 542A, which are located on oppositesides of the base prism holder 541A such that the wedge-shaped prism540A supported by the base prism holder 541A intervenes between theslide bases 542A, 542A. The axial air separation adjusting section 54still further comprises a sliding section 545, which is provided withthe wedge-shaped prism 540B, a prism holder 541B for supporting thewedge-shaped prism 540B, and sliders 542B, 542B. The sliders 542B, 542Bare located on opposite sides of the prism holder 541B such that thewedge-shaped prism 540B supported by the prism holder 541B intervenesbetween the sliders 542B, 542B. The sliders 542B, 542B are capable ofmoving on the slide bases 542A, 542A. The axial air separation adjustingsection 54 also comprises an actuating section 546, which is secured tothe base prism holder 541A in order to move the sliding section 545.

By way of example, the wedge-shaped prism 540A and the wedge-shapedprism 540B constituting the wedge-shaped prism pair 540 may be formed inthe manner described below. Specifically, as illustrated in FIG. 5, aplane-parallel plate made from a transparent material, such as glass oran acrylic resin, may be cut along an oblique plane Hk, which isinclined with respect to parallel planes H11 and H22 of theplane-parallel plate, and a pair of wedge-shaped prisms A and B may thusbe formed. The pair of the thus formed wedge-shaped prisms A and B maybe utilized as the pair of the wedge-shaped prisms described above. Inthis embodiment, each of the wedge-shaped prism 540A and thewedge-shaped prism 540B is made from glass having a refractive index of1.51.

The wedge-shaped prism 540A and the wedge-shaped prism 540B aresupported respectively by the base prism holder 541A and the prismholder 541B, such that a plane-parallel plate may be formed by thecombination of the wedge-shaped prism 540A and the wedge-shaped prism540B with an air layer 550 of a thickness “t” (e.g., 10 μm) interveningbetween the wedge-shaped prism 540A and the wedge-shaped prism 540B.Also, a linear slide is constituted by the combination of the slidebases 542A, 542A and the sliders 542B, 542B. The actuating section 546moves the sliding section 545 in one direction (i.e., the directionindicated by the double headed arrow U in FIG. 4), and the wedge-shapedprism 540B is thus moved with respect to the wedge-shaped prism 540Asuch that the thickness “t” of the air layer 550 intervening between thewedge-shaped prism 540A and the wedge-shaped prism 540B may not vary.With the movement of the sliding section 545, the substantial thicknessof the plane-parallel plate, which is formed by the combination of thepair of the wedge-shaped prism 540A and the wedge-shaped prism 540B,(i.e., the thickness obtained by subtracting the thickness “t” of theair layer 550 from the thickness of the plane-parallel plate formed inthe manner described above) is altered. With the alteration of thesubstantial thickness of the plane-parallel plate, which is formed bythe combination of the pair of the wedge-shaped prism 540A and thewedge-shaped prism 540B, the adjustment of the axial air separationbetween the second image forming optical system 52 and thephotosensitive material 150 is performed. The value obtained from themultiplication of the substantial thickness of the plane-parallel plate,which is formed by the combination of the pair of the wedge-shaped prism540A and the wedge-shaped prism 540B, by the refractive index of theplane-parallel plate represents the axial air separation represented bythe plane-parallel plate, i.e. the value resulting from the conversionof the thickness of the plane-parallel plate into the air thickness.

The angle of a plane H2 of the wedge-shaped prism 540A, which planeconstitutes one of the parallel planes of the plane-parallel platedescribed above, with respect to an oblique surface H1 of thewedge-shaped prism 540A is equal to 5 degrees. Also, the angle of aplane H4 of the wedge-shaped prism 540B, which plane constitutes theother parallel plane of the plane-parallel plate described above, withrespect to an oblique surface H3 of the wedge-shaped prism 540B is equalto 5 degrees. The distance of movement of the sliding section 545actuated by the actuating section 546 is equal to 10 mm. In cases wherethe sliding section 545 is moved by the distance of 10 mm, the thicknessof the plane-parallel plate, which is formed by the combination of thepair of the wedge-shaped prism 540A and the wedge-shaped prism 540B,alters by 870 μm. Therefore, with the alteration of the thickness of theplane-parallel plate by 870 μm, a quantity of alteration of the focusposition (i.e., the quantity of the adjustment of the focusing point atthe time of the formation of the image of the two-dimensional pattern ofthe light described above) becomes equal to 294 μm. Specifically, analteration quantity δ of the focus position described above may becalculated with the formula shown below.δ=ε((n−1)/n)wherein ε represents the alteration quantity of the thickness of theplane-parallel plate, which is formed by the combination of the pair ofthe wedge-shaped prism 540A and the wedge-shaped prism 540B, and nrepresents the refractive index of the plane-parallel plate.

In this case, since the alteration quantity ε of the thickness of theplane-parallel plate, which is formed by the combination of the pair ofthe wedge-shaped prism 540A and the wedge-shaped prism 540B, is equal to870 μm, and the refractive index “n” of the plane-parallel plate isequal to 1.51, the alteration quantity δ of the focus position describedabove may be calculated as δ=294 μm.

The base prism holder 541A and the prism holder 541B are respectivelyprovided with an aperture 543A and aperture 543B. The aperture 543A andaperture 543B allow the passage of the light, which has been radiatedout from the second image forming optical system 52, through the pair ofthe wedge-shaped prism 540A and the wedge-shaped prism 540B toward thephotosensitive material 150.

In the actuating section 546, a thimble 547 a of a micrometer head 547is rotated by a stepping motor 548, and a spindle 547 b of themicrometer head 547 is thus moved forward and backward. The slidingsection 545 is moved in this manner.

The axial air separation adjusting section 54 is located such that theplane H2 and the plane H4, which constitute the parallel planes of theplane-parallel plate formed by the combination of the pair of thewedge-shaped prism 540A and the wedge-shaped prism 540B may extend inthe direction, which is normal to the direction of the optical axis ofthe second image forming optical system 52 (i.e., the directionindicated by the arrow Z in FIG. 4), and such that the direction of themovement of the sliding section 545 may coincide with the direction,which is associated with the minimum width of each of the regions of theformation of the image of the two-dimensional pattern on thephotosensitive material 150, (i.e., the sub-scanning direction in FIG.8A, which will be described later). Specifically, the axial airseparation adjusting section 54 is located such that the direction ofthe component of the movement of the sliding section 545 along thedirection, which is normal to the optical axis direction (i.e., the Zdirection), and the direction associated with the minimum width of eachof the regions of the formation of the image of the two-dimensionalpattern, which image is formed through the image-side telecentric imageforming optical system described above and on the photosensitivematerial 150, (i.e., the direction in which the width of each of theregions of the formation of the image of the two-dimensional patternbecomes minimum in the direction normal to the Z direction describedabove) may coincide with each other.

The wedge-shaped prism pair 540 are provided with coating layers, suchthat the transmittance with respect to the light to which thephotosensitive material 150 is exposed, i.e. blue light produced by thelight source unit 60 as will be described later, may be at least 99.5%,and such that the reflectivity of each of the oblique surface H1 of thewedge-shaped prism 540A and the oblique surface H3 of the wedge-shapedprism 540B, which wedge-shaped prisms are adjacent to each other withthe air layer 550 intervening therebetween, with respect to red lighthaving wavelengths different from the wavelengths of the blue lightdescribed above may be at least 3%. Therefore, the parallelism betweenthe oblique surface H1 and the oblique surface H3 and an alteration ofthe separation between the oblique surface H1 and the oblique surface H3are capable of being measured with a process, wherein the state ofinterference of the coherent red light, which has been reflected fromthe oblique surface H1, and the coherent red light, which has beenreflected from the oblique surface H3, is measured. Accordingly, acorrection is capable of being made with respect to an error in movementof the sliding section 545, such that alterations of components of thelight beams Lb, Lb, . . . , which have passed through the wedge-shapedprism pair 540, toward the direction normal to the optical axisdirection (i.e., the Z direction) at the time of the travel of the lightbeams Lb, Lb, . . . toward the photosensitive material 150 may besuppressed.

In cases where microlenses having a short focal length (e.g., a focallength of 190 μm) are utilized as the microlenses 55 a, 55 a, . . . ofthe microlens array 55, even if the aberrations of the first imageforming optical system 51 are comparatively large, variations in waistpositions (focusing points) of the light beams having passed through themicrolens array 55 will be capable of being suppressed. Therefore, incases where the microlens array 55, the second image forming opticalsystem 52, which is the image-side telecentric image forming opticalsystem, and the axial air separation adjusting section 54 are combinedwith one another, the adjustment of the focusing point is capable ofbeing performed more quickly and more easily.

The embodiment of the projecting exposure apparatus in accordance withthe present invention, which comprises the exposure head 166 providedwith the optical system 50, the axial air separation adjusting section54, and the like, will hereinbelow be described in detail.

Explanation of Entire Constitution of the Projecting Exposure Apparatus

FIG. 6 is a perspective view showing an appearance of the embodiment ofthe projecting exposure apparatus in accordance with the presentinvention. FIG. 7 is a perspective view showing how an exposureoperation is performed by the projecting exposure apparatus of FIG. 6.FIG. 8A is a plan view showing exposure-processed regions, which areformed on a photosensitive material. FIG. 8B is an explanatory viewshowing an array of exposure processing areas, each of which issubjected to exposure processing performed by one of exposure heads.

As illustrated in FIG. 6, the embodiment of the projecting exposureapparatus in accordance with the present invention comprises a scannerunit 162 and a main body section for supporting the scanner unit 162.The main body section is provided with a flat plate-like stage 152 forsupporting the photosensitive material 150 on the surface by suction.The main body section is also provided with a support base 156 and twoguides 158, 158 secured to the surface of the support base 156. Theguides 158, 158 extend in a sub-scanning direction and support the stage152 such that the stage 152 is capable of moving in the sub-scanningdirection. The stage 152 is supported by the guides 158, 158 such thatthe stage 152 is capable of reciprocally moving in the sub-scanningdirection. The stage 152 is located such that the longitudinal directionof the stage 152 coincides with the sub-scanning direction. Theprojecting exposure apparatus is provided with an actuating section (notshown) for moving the stage 152 along the guides 158, 158.

A scanner support section 160 having a portal shape is located at amiddle part of the support base 156. The scanner support section 160extends over the movement path of the stage 152 and supports the scannerunit 162. The scanner support section 160 supports the scanner unit 162on one side of the scanner support section 160, which side is taken withrespect to the sub-scanning direction. The scanner support section 160is provided with two detection sensors 164, 164 on the other side of thescanner support section 160, which side is taken with respect to thesub-scanning direction. The detection sensors 164, 164 detect a leadingend and a tail end of the photosensitive material 150. The scanner unit162 and the detection sensors 164, 164 are thus secured to the oppositesides of the scanner support section 160 and are located above themovement path of the stage 152. The scanner unit 162 and the detectionsensors 164, 164 are connected to a controller (not shown) forcontrolling the scanner unit 162 and the detection sensors 164, 164. InFIG. 6, the reference numerals 154, 154, . . . represent pillars.

As illustrated in FIG. 7 and FIGS. 8A, 8B, the scanner unit 162 isprovided with a plurality of (e.g., 14) exposure heads 166, 166, . . .for irradiating the exposure light to the photosensitive material 150.The exposure heads 166, 166, . . . are arrayed approximately in amatrix-like pattern composed of “m” number of rows and “n” number ofcolumns (e.g., three rows and five columns).

In this embodiment, in accordance with the width of the photosensitivematerial 150, five exposure heads 166, 166, . . . are located along eachof the first and second rows, and four exposure heads 166, 166, . . .are located along the third row. In cases where a certain exposure head166 in the array of the exposure heads 166, 166, . . . , which exposurehead is located at a position of an m'th row and an n'th column in thearray of the exposure heads 166, 166, . . . is to be represented, thecertain exposure head 166 is herein represented as an exposure head 166_(mn).

As illustrated in FIG. 8B, an exposure processing area 168 _(mn)corresponding to each exposure head 166 _(mn), which exposure processingarea is subjected to the exposure processing performed by the exposurehead 166 _(mn), has a rectangular shape, whose short side extends alongthe sub-scanning direction, i.e. the rectangular shape, in which thedirection of the minimum width coincides with the sub-scanningdirection. As illustrated in FIG. 8A, as the stage 152 moves along thesub-scanning direction, a band-shaped exposure-processed region 170_(mn) corresponding to each exposure head 166 _(mn) is formed on thephotosensitive material 150.

As illustrated in FIG. 8B, in the array of the exposure heads 166, 166,. . . of the scanner unit 162, a row of the exposure heads 166, 166, . .. and an adjacent row of the exposure heads 166, 166, . . . are shiftedby a predetermined distance from each other with respect to a mainscanning direction, which is normal to the sub-scanning directiondescribed above. Such that the band-shaped exposure-processed regions170, 170, . . . may be formed on the photosensitive material 150 withoutany unprocessed space being left between the band-shapedexposure-processed regions 170, 170, . . . in the main scanningdirection, the areas, which are located between, for example, anexposure processing area 168 ₁₁ and an exposure processing area 168 ₁₂corresponding respectively to an exposure head 166 ₁₁ and an exposurehead 166 ₁₂ located along the first row, and which are not capable ofbeing subjected to the exposure processing performed by the exposurehead 166 ₁₁ and the exposure head 166 ₁₂, are exposure-processed with anexposure head 166 ₂₁, which is located along the second row andcorresponds to an exposure processing area 168 ₂₁, and an exposure head166 ₃₁, which is located along the third row and corresponds to anexposure processing area 168 ₃₁.

Each of the exposure heads 166, 166, . . . is constituted of the lightsource unit 60 described above, the DMD 80 described above, the opticalsystem 50 described above, and a DMD irradiation optical system 70,which receives the light for exposure from the light source unit 60 andirradiates the light to the DMD 80. The light having been obtained fromthe spatial light modulation performed by the DMD 80 is guided onto thephotosensitive material 150, and the photosensitive material 150 is thusexposed to the light.

Explanation of Elements Constituting the Exposure Head 166

The elements constituting each of the exposure heads 166, 166, . . .will be described hereinbelow. The optical system 50 and the axial airseparation adjusting section 54 have the constitutions described above.

Light Source Unit 60

The light source unit 60 comprises a plurality of (e.g., six) laser beamcombining light sources 40, 40, . . . The light source unit 60 alsocomprises a laser beam radiating section 61. The laser beam radiatingsection 61 units a plurality of optical fibers 31, 31, . . . , each ofwhich is connected to one of multimode optical fibers 30, 30, . . . Eachof the multimode optical fibers 30, 30, . . . acts as a constituentelement of one of the laser beam combining light sources 40, 40, . . .

Explanation of the Laser Beam Combining Light Source 40

FIG. 9 is a plan view showing a laser beam combining light source. FIG.10 is a side view showing the laser beam combining light source. FIG. 11is a front view showing the laser beam combining light source. FIG. 12is an enlarged plan view showing optical elements of the laser beamcombining light source.

Constitution of the Laser Beam Combining Light Source 40

Each of the laser beam combining light sources 40, 40, . . . comprises aplurality of semiconductor lasers LD1, LD2, LD3, LD4, LD5, LD6, and LD7.The laser beam combining light source 40 also comprises the onemultimode optical fiber 30. The laser beam combining light source 40further comprises a combination of collimator lenses 11 to 17 and oneconverging lens 20. The combination of the collimator lenses 11 to 17and the converging lens 20 acts as laser beam converging means forconverging an entire laser beam, which is composed of laser beams havingbeen produced by the plurality of the semiconductor lasers LD1 to LD7,and irradiating the entire laser beam onto a core region of themultimode optical fiber 30. The laser beams constituting the entirelaser beam are combined with one another in the multimode optical fiber30. The combined laser beam passes through the multimode optical fiber30 and is radiated out from the multimode optical fiber 30.

More specifically, the laser beam combining light source 40 comprisesthe plurality of (e.g., seven) chip-like GaN type semiconductor lasersLD1, LD2, LD3, LD4, LD5, LD6, and LD7, which may be of a transversemultimode or a single mode. The GaN type semiconductor lasers LD1, LD2,LD3, LD4, LD5, LD6, and LD7 are arrayed in one direction and secured toa top surface of a heat block 10, which is made from a material having ahigh heat transfer coefficient, such as copper. The laser beam combininglight source 40 also comprises the collimator lenses 11, 12, 13, 14, 15,16, and 17, which correspond respectively to the GaN type semiconductorlasers LD1, LD2, LD3, LD4, LD5, LD6, and LD7. The laser beam combininglight source 40 further comprises the converging lens 20 for convergingthe entire laser beam, which is composed of the laser beams having beenradiated out from the collimator lenses 11 to 17, into one spot. Thelaser beam combining light source 40 still further comprises the onemultimode optical fiber 30 for receiving the entire laser beam, whichhas been converted by the converging lens 20, and combining the laserbeams constituting the entire laser beam with one another.

The number of the semiconductor lasers LD1, LD2, . . . is not limited toseven. For example, laser beams having been produced by 20 semiconductorlasers may be irradiated to a multimode optical fiber, which has acladding layer diameter of 60 μm, a core diameter of 50 μm, and NA of0.2.

The laser beams produced by the GaN type semiconductor lasers LD1 to LD7may have an identical wavelength (of, e.g., 405 nm). Also, the GaN typesemiconductor lasers LD1 to LD7 may have an identical maximum outputpower (e.g., 100 mW in the cases of multimode lasers, or 30 mW in thecases of single mode lasers) Alternatively, as the GaN typesemiconductor lasers LD1 to LD7, lasers capable of producing laserbeams, which have a wavelength other than 405 nm and falling within theblue light wavelength range of 350 nm to 450 nm, may be employed.

As illustrated in FIG. 9, FIG. 10, and FIG. 11, the optical elements ofthe laser beam combining light source 40 are accommodated within abox-like package 41, which has an opening at the top region. The package41 is provided with a package cover 49 capable of closing the opening ofthe package 41. After the box-like package 41 is subjected to deaerationprocessing, a sealing gas is introduced into the package 41, and theopening of the package 41 is closed by the package cover 49. In thismanner, the closed space (sealed space), which is surrounded by thepackage 41 and the package cover 49, is hermetically sealed.

A base plate 42 is secured to an inside bottom surface of the package41. The heat block 10 described above, a converging lens holder 45 forsupporting the converging lens 20, and a fiber holder 46 for supportingan entry end section of the multimode optical fiber 30 are secured to atop surface of the base plate 42. A radiating end section of themultimode optical fiber 30 is drawn out through an aperture, which isformed through a side wall of the package 41, to the exterior of thepackage 41.

The temperature of the base plate 42 is adjusted by temperatureadjusting means, which utilizes a fluid as a medium, a Peltier device(not shown), or the like. While the projecting exposure apparatus isbeing operated, the temperature of the base plate 42 is kept at apredetermined value.

A collimator lens holder 44 is secured to a side surface of the heatblock 10. The collimator lenses 11 to 17 are supported by the collimatorlens holder 44. Also, electric wires 47, 47, . . . for supplyingactuating electric currents to the GaN type semiconductor lasers LD1 toLD7 are drawn out through an aperture, which is formed through a sidewall of the package 41.

In FIG. 9 and FIG. 10, as an aid in facilitating the explanation, onlythe GaN type semiconductor lasers LD1 and LD7 among the plurality of theGaN type semiconductor lasers LD1 to LD7 are numbered. Also, only thecollimator lenses 11 and 17 among the plurality of the collimator lenses11 to 17 are numbered.

FIG. 11 is a front view showing the part at which the collimator lenses11 to 17 are fitted. Each of the collimator lenses 11 to 17 is anaspherical lens and is formed in a slender shape such that a regioncontaining the optical axis of the aspherical lens has been cut alongplanes parallel to the optical axis. Each of the collimator lenses 11 to17 having the slender shape may be formed with, for example, a resinshaping process or a glass shaping process. The collimator lenses 11 to17 are located at positions which are close to one another and whichstand side by side along the array direction of light emission points ofthe GaN type semiconductor lasers LD1 to LD7 (i.e., the horizontaldirection in FIG. 11), such that the longitudinal direction of each ofthe collimator lenses 11 to 17 may be normal to the array direction ofthe light emission points of the GaN type semiconductor lasers LD1 toLD7 (i.e., the horizontal direction in FIG. 11).

Each of the GaN type semiconductor lasers LD1 to LD7 may be providedwith an active layer having a light emission width of 2 μm. The GaN typesemiconductor lasers LD1 to LD7 may produce laser beams B1 to B7,respectively, in a state such that a spread angle with respect to thedirection parallel to the surface of the active layer is, for example,10°, and such that the spread angle with respect to the direction normalto the surface of the active layer is, for example, 30°.

Each of the GaN type semiconductor lasers LD1 to LD7 is located in anorientation such that the surface of the active layer may be parallel tothe array direction of the light emission points of the GaN typesemiconductor lasers LD1 to LD7. Specifically, the direction, which isassociated with the large spread angle of each of the laser beams B1 toB7 radiated out respectively from the light emission points describedabove, coincides with the longitudinal direction of each of thecollimator lenses 11 to 17 having the slender shape. Also, thedirection, which is associated with the small spread angle of each ofthe laser beams B1 to B7 radiated out respectively from the lightemission points described above, coincides with the lateral direction ofeach of the collimator lenses 11 to 17.

The length of each of the collimator lenses 11 to 17, which length istaken along the longitudinal direction of each of the collimator lenses11 to 17, may be equal to 4.6 mm. The width of each of the collimatorlenses 11 to 17, which width is taken along the lateral direction ofeach of the collimator lenses 11 to 17, may be equal to 1.1 mm. Also,the length of a major axis of the elliptic beam shape of each of thelaser beams B1 to B7 incident upon the collimator lenses 11 to 17,respectively, may be equal to 2.6 mm. The length of a minor axis of theelliptic beam shape of each of the laser beams B1 to B7 incident uponthe collimator lenses 11 to 17, respectively, may be equal to 0.9 mm.Each of the collimator lenses 11 to 17 may be constituted such that afocal length f is equal to 3 mm, NA is equal to 0.6, and a lens arraypitch is equal to 1.25 mm.

The converging lens 20 is formed in a slender shape such that a regioncontaining the optical axis of an aspherical lens has been cut alongplanes parallel to the optical axis. The converging lens 20 is locatedin an orientation such that the longitudinal direction of the converginglens 20 coincides with the array direction of the collimator lenses 11to 17, and such that the lateral direction of the converging lens 20coincides with the direction normal to the array direction of thecollimator lenses 11 to 17.

The converging lens 20 is constituted such that a focal length f isequal to 23 mm, and NA is equal to 0.2. The converging lens 20 may beformed with, for example, a resin shaping process or a glass shapingprocess.

Operation of the Laser Beam Combining Light Source 40

Each of the laser beams B1, B2, B3, B4, B5, B6, and B7, which have beenradiated out respectively from the GaN type semiconductor lasers LD1,LD2, LD3, LD4, LD5, LD6, and LD7 constituting the laser beam combininglight source 40 described above, is collimated by the corresponding oneof the collimator lenses 11 to 17. The laser beams B1 to B7 having thusbeen collimated are converged by the converging lens 20 and impinge uponthe entry end face of a core section 30 a of the multimode optical fiber30.

The laser beams B1 to B7 having thus been collimated by the converginglens 20 enter into the core section 30 a of the multimode optical fiber30 and are combined into a combined laser beam B. The combined laserbeam B travels through the multimode optical fiber 30 and is radiatedout from a radiating end face of the multimode optical fiber 30. Thecombined laser beam B having thus been radiated out from the radiatingend face of the multimode optical fiber 30 impinges upon an opticalfiber 31 connected to the multimode optical fiber 30 as will bedescribed later.

For example, in cases where a coupling efficiency of the laser beams B1to B7 with the multimode optical fiber 30 is equal to 0.85, and theoutput power of each of the GaN type semiconductor lasers LD1 to LD7 isequal to 30 mW, the combined laser beam B is capable of being obtainedwith an output power of 180 mW (=30 mW×0.85×7). The combined laser beamB obtained with the output power described above travels through themultimode optical fiber 30 to the optical fiber 31. Therefore, theoutput power obtained at the laser beam radiating section 61 describedbelow, at which the six optical fibers 31, 31, . . . connectedrespectively to the multimode optical fibers 30, 30, . . . of the laserbeam combining light sources 40, 40, . . . are united together, becomesequal to approximately 1 W (=180 mW×6).

Laser Beam Radiating Section 61

The laser beam radiating section 61 will be described hereinbelow withreference to FIGS. 13A, 13B and FIG. 14. FIG. 13A is a perspective viewshowing how multimode optical fibers of the laser beam combining lightsources are connected to optical fibers of a laser beam radiatingsection in a light source unit. FIG. 13B is an enlarged view showing apart of the laser beam radiating section. FIG. 13C is a front viewshowing an example of an array of the optical fibers at the laser beamradiating section. FIG. 13D is a front view showing a different exampleof an array of the optical fibers at the laser beam radiating section.FIG. 14 is a view showing how the multimode optical fiber of the laserbeam combining light source and the optical fiber at the laser beamradiating section are connected to each other.

As illustrated in FIGS. 13A and 13B, the laser beam radiating section 61described above comprises the optical fibers 31, 31, . . . , supportplates 65, 65, and a protective plate 63. The laser beam radiatingsection 61 is constituted in the manner described below.

As illustrated in FIG. 13A, the radiating end of each of the multimodeoptical fibers 30, 30, . . . of the laser beam combining light sources40, 40, . . . is connected to the entry end of the corresponding one ofthe optical fibers 31, 31, . . . of the laser beam radiating section 61.The entry end of each of the optical fibers 31, 31, . . . has a corediameter, which is identical with the core diameter of the multimodeoptical fiber 30, and a cladding layer diameter, which is smaller thanthe cladding layer diameter of the multimode optical fiber 30. Also, asillustrated in FIG. 13C, the radiating ends of the optical fibers 3, 31,. . . are arrayed in a row and thus constitute a radiating end section68. Alternatively, as illustrated in FIG. 13D, the radiating ends of theoptical fibers 31, 31, . . . may be stacked and arrayed in two rows andmay thus constitute a radiating end section 68′.

As illustrated in FIG. 13B, the portions of the optical fibers 31, 31, .. . located on the radiating side are sandwiched between the two supportplates 65, 65 having flat surfaces and are thus secured in predeterminedpositions. Also, the protective plate 63, which is transparent and ismade from glass, or the like, for protecting the end faces of theoptical fibers 31, 31, . . . on the radiating side, is located at theend faces of the optical fibers 31, 31, . . . on the radiating side. Theprotective plate 63 may be located such that it is in close contact withthe radiating end faces of the optical fibers 31, 31, . . .Alternatively, the protective plate 63 may be located such that it isnot in close contact with the radiating end faces of the optical fibers31, 31, . . .

The connection of the optical fiber 31 and the multimode optical fiber30 to each other may be made in the manner illustrated in FIG. 14.Specifically, the end face of the optical fiber 31 having the smallcladding layer diameter is connected co-axially to a small-diameterregion 30 c of the end face of the multimode optical fiber 30 having thelarge cladding layer diameter. The connection may be performed with, forexample, a fusion bonding process.

Alternatively, the connection of the optical fiber 31 and the multimodeoptical fiber 30 to each other may be made in the manner describedbelow. Specifically, a short optical fiber may be prepared with aprocess, wherein an optical fiber having a short length and a smallcladding layer diameter is fusion-bonded to an optical fiber having ashort length and a large cladding layer diameter. The short opticalfiber may then be connected to the radiating end of the multimodeoptical fiber 30 via a ferrule, an optical connector, or the like. Incases where the optical fiber 31 and the multimode optical fiber 30 arereleasably connected to each other by the utilization of the connector,or the like, the optical fiber having the small cladding layer diameteris capable of being exchanged easily at the time of the breakage, or thelike, and the cost required for the maintenance operations for theexposure head is capable of being kept low.

Each of the multimode optical fiber 30 and the optical fiber 31 may be astep index type optical fiber, a graded index type optical fiber, or acomposite type optical fiber. For example, a step index type opticalfiber, which is supplied by Mitsubishi Densen Kogyo, K.K., may beutilized as each of the multimode optical fiber 30 and the optical fiber31. In this embodiment, each of the multimode optical fiber 30 and theoptical fiber 31 is constituted of the step index type optical fiber.

The multimode optical fiber 30 is constituted such that the claddinglayer diameter is equal to 125 μm, the core diameter is equal to 50 μm,NA is equal to 0.2, and the transmittance of the entry end face coatinglayer is equal to at least 99.5%. The optical fiber 31 is constitutedsuch that the cladding layer diameter is equal to 60 μm, the corediameter is equal to 50 μm, and NA is equal to 0.2.

DMD 80

The DMD 80 will be described herein below. FIG. 15A is a plan viewshowing how the photosensitive material is exposed to light beams incases where the DMD is located in an orientation, which is not oblique.FIG. 15B is a plan view showing how the photosensitive material isexposed to the light beams in cases where the DMD is located in anoblique orientation.

As described above with reference to FIG. 1 and FIG. 2, each of theexposure heads 166, 166, . . . is provided with the digital micromirrordevice (DMD) 80 (shown in FIG. 3) acting as the spatial light modulationmeans for modulating the incident later beam in accordance with apredetermined control signal. The DMD 80 is connected to a controller(not shown), which is provided with a signal processing section and amirror actuation control section. In accordance with a received imagesignal, the signal processing section of the controller forms thecontrol signal for controlling the actuation of each of the micromirrors81, 81, . . . of the DMD 80. The control signal is formed for each ofthe exposure heads 166, 166, . . . Also, in accordance with the controlsignal having been formed by the signal processing section, the mirroractuation control section of the controller controls the angle of thereflection surface of each of the micromirrors 81, 81, . . . of the DMD80 of each of the exposure heads 166, 166, . . .

The DMD 80 comprises an array of the micromirrors 81, 81, . . . , whicharray is composed of a plurality of (e.g., 1,024) columns of themicromirrors 81, 81, . . . standing side by side with respect to thelongitudinal direction of the DMD 80 and a plurality of (e.g., 756) rowsof the micromirrors 81, 81, . . . standing side by side with respect tothe lateral direction of the DMD 80. As illustrated in FIG. 15B, incases where the DMD 80 is located in an oblique orientation, the pitchof scanning loci (i.e., the sub-scanning lines) along the sub-scanningdirection, which are formed with the laser beams having been reflectedfrom the micromirrors 81, 81, . . . of the DMD 80, is capable of beingset at a small pitch P2. The pitch P2 is smaller than a pitch P1obtained in cases where the DMD 80 is located in an orientation, whichis not oblique, as illustrated in FIG. 15A. With the setting of theinclination of the DMD 80, the resolution of exposure with the exposurehead 166 is capable of being enhanced markedly.

Also, since an identical region of the photosensitive material 150 onthe sub-scanning line is capable of being subjected to multiple exposurewith different micromirrors 81, 81, . . . , the exposed position iscapable of being controlled finely, and a high-definition exposureoperation is capable of being performed. Further, joints of thetwo-dimensional patterns, which are formed with the exposure to thelaser beams radiated out from the exposure heads 166, 166, . . .adjacent to one another with respect to the main scanning direction, arecapable of being rendered imperceptible.

DMD Irradiation Optical System 70

As illustrated in FIG. 2, the DMD irradiation optical system 70 of eachof the exposure heads 166, 166, . . . comprises a collimator lens 71 forapproximately collimating the plurality of the laser beams, which havebeen radiated out from the laser beam radiating section 61 of the lightsource unit 60, as a whole. The DMD irradiation optical system 70 alsocomprises a micro fry-eye lens 72, which is located in the optical pathof the light having passed through the collimator lens 71. The DMDirradiation optical system 70 further comprises a micro fry-eye lens 73,which is located so as to stand facing the micro fry-eye lens 72. TheDMD irradiation optical system 70 still further comprises a field lens74, which is located on the radiating side of the micro fry-eye lens 73,i.e. on the side facing the mirror 75 described later. The DMDirradiation optical system 70 also comprises the prism 76.

Each of the micro fry-eye lens 72 and the micro fry-eye lens 73comprises a plurality of fine lens cells, which are arrayed intwo-dimensional directions. The laser beams having passed through thefine lens cells impinge in an overlapping state upon the DMD 80 via themirror 75 and the prism 76. Therefore, the distribution of theintensities of the laser beams impinging upon the DMD 80 is capable ofbeing rendered uniform.

The mirror 75 reflects the laser beams having passed through the fieldlens 74. Also, the prism 76 is the TIR prism (the total reflectionprism) and totally reflects the laser beams, which have been reflectedfrom the mirror 75, toward the DMD 80. In the manner described above,the DMD irradiation optical system 70 irradiates the laser beams, whichhave the approximately uniform intensity distribution, onto the DMD 80.

Explanation of the Operation of the Projecting Exposure Apparatus

How the aforesaid projecting exposure apparatus operates will bedescribed hereinbelow.

The projecting exposure apparatus is actuated, and the respectivesections of the projecting exposure apparatus are set in an operatingstate. In this state, the temperature of the laser beam combining lightsources 40, 40, . . . of each of the exposure heads 166, 166, . . . isadjusted. However, the GaN type semiconductor lasers LD1 to LD7 of eachof the laser beam combining light sources 40, 40, . . . are not turnedon.

The image signal corresponding to the two-dimensional pattern is fedinto the controller (not shown), which is connected to the DMD 80 ofeach of the exposure heads 166, 166, . . . The image signal is stored ina frame memory of the controller. The image signal represents the imagedensities of the pixels constituting the image. By way of example, theimage signal may represent the image density of each pixel by the binarynotation (representing whether a dot is to be or is not to be recorded).

The stage 152 having the surface, on which the photosensitive material150 has been supported by suction, is moved by the actuating section(not shown) at a predetermined speed from the side more upstream thanthe scanner support section 160 to the side more downstream than thescanner support section 160 along the guides 158, 158 and under thescanner support section 160. At the time at which the stage 152 passesunder the scanner support section 160, the leading end of thephotosensitive material 150 is detected by the detection sensors 164,164, which are secured to the scanner support section 160. After theleading end of the photosensitive material 150 has been detected by thedetection sensors 164, 164, the image signal components of the imagesignal, which has been stored in the frame memory of the controller, aresuccessively read from the frame memory in units of a plurality ofscanning lines. In accordance with the thus read image signal componentsof the image signal, the signal processing section forms the controlsignal for each of the exposure heads 166, 166, . . .

When preparations for the exposure operation on the photosensitivematerial 150 has been made, the GaN type semiconductor lasers LD1 to LD7of each of the laser beam combining light sources 40, 40, . . . of eachof the exposure heads 166, 166, . . . are turned on. In accordance withthe control signal having been formed by the signal processing section,each of the micromirrors 81, 81, . . . of the DMD 80 of each of theexposure heads 166, 166, . . . is controlled by the mirror actuationcontrol section of the controller. The photosensitive material 150 isthus exposed to the laser beams.

When the laser beams, which have been produced by the laser beamcombining light sources 40, 40, . . . and have been radiated out fromthe laser beam radiating section 61, are irradiated to the DMD 80 viathe DMD irradiation optical system 70 in each of the exposure heads 166,166, . . . , the laser beams are reflected from the micromirrors 81, 81,. . . of the DMD 80, which micromirrors are in the on state. The thusreflected laser beams pass through the optical system 50, and the imagesof the laser beams are formed on the photosensitive surface 151 of thephotosensitive material 150. The images of the laser beams reflectedfrom the micromirrors 81, 81, . . . of the DMD 80, which micromirrorsare in the off state, are not formed on the photosensitive surface 151.Therefore, the photosensitive material 150 is not exposed to the laserbeams reflected from the micromirrors 81, 81, . . . of the DMD 80, whichmicromirrors are in the off state.

In the manner described above, the laser beams, which have been radiatedout from the light source unit 60 of each of the exposure heads 166,166, . . . , are on-off modulated for each of the micromirrors 81, 81, .. . of the DMD 80 (i.e., for each of the pixels). As illustrated in FIG.7 and FIGS. 8A, 8B, each of the exposure processing areas 168, 168, . .. on the photosensitive material 150 is subjected to the exposureprocessing performed by one of the exposure heads 166, 166, . . . Also,the photosensitive material 150 is moved in the sub-scanning directiontogether with the stage 152, and each of the band-shapedexposure-processed regions 170, 170, . . . extending in the sub-scanningdirection is formed by one of the exposure heads 166, 166, . . .

Ordinarily, warpage or waviness (warpage or waviness of, for example,approximately 100 μm) occurs with the photosensitive material 150.Therefore, the separation between each exposure head 166 _(mn) and theexposure region of the photosensitive material 150, which exposureregion is exposed to the laser beams radiated out from the exposure head166 _(mn), is detected by separation detecting means (not shown), suchas a gap sensor, for detecting the separation in accordance with analteration in position, from which the laser beams are reflected. Also,information representing the results of the detection of the separationis fed into an axial air separation adjustment control section (notshown), and the axial air separation adjustment control section controlsthe axial air separation adjusting section 54 in order to correct thealteration in separation described above. In this manner, the adjustmentof the axial air separation between the second image forming opticalsystem 52, which is the image-side telecentric image forming opticalsystem, and the photosensitive material 150 is performed.

Use of Part of the DMD 80

In this embodiment, as illustrated in FIGS. 16A and 16B, the DMD 80comprises the array of the micromirrors 81, 81, . . . , which array iscomposed of the plurality of (e.g., 1,024) columns (pixels) of themicromirrors 81, 81, . . . standing side by side with respect to thelongitudinal direction of the DMD 80 (corresponding to the main scanningdirection in the exposure operation) and a plurality of (e.g., 756) rows(pixels) of the micromirrors 81, 81, . . . standing side by side withrespect to the lateral direction of the DMD 80 (corresponding to thesub-scanning direction in the exposure operation). However, in thisembodiment, the controller controls such that only certain rows of themicromirrors 81, 81, . . . (e.g., 1,024 micromirrors×300 rows) areactuated.

For example, as illustrated in FIG. 16A, only the micromirrors 81, 81, .. . located in an array region 80C of the DMD 80, which array region isconstituted of certain middle rows, may be actuated. Alternatively, asillustrated in FIG. 16B, only the micromirrors 81, 81, . . . located inan array region 80T of the DMD 80, which array region is constituted ofcertain rows at an end area, may be actuated. Also, in cases where afailure occurs with a certain micromirror 81, the micromirrors 81, 81, .. . located in an array region other than the array region containingthe defective micromirror 81 may be utilized. In this manner, the arrayregion of the DMD 80 to be used may be altered in accordance with thecondition of the operation.

Specifically, limitation is imposed upon the signal processing speed forthe DMD 80, and the modulation speed per scanning line is determined inproportion to the number of the micromirrors 81, 81, . . . to becontrolled (i.e., the number of the pixels). Therefore, in cases whereonly the micromirrors 81, 81, . . . located within a certain part of thearray region of the DMD 80 are used, the modulation speed per scanningline is capable of being kept high. In such cases, since only part ofthe pixel sections constituting the DMD 80 is used, the processing widthin the sub-scanning direction is capable of being kept narrow.Therefore, the distance of the movement of the wedge-shaped prism 540Bwith respect to the wedge-shaped prism 540A is capable of being keptshort. Also, in cases where the processing width, over which theadjustment of the focusing point is to be performed, is kept narrow, thewaviness occurring with the region of the photosensitive material 150,which region has the narrow width, is capable of being kept small.Therefore, the adjustment of the focusing point is capable of beingperformed more accurately.

In cases where the region of the DMD 80, which region is used in themanner described above, is altered, the regions of the formation of theimage of the two-dimensional pattern on the photosensitive material 150,which image is formed by the optical system 50, alter in accordance withthe alteration of the region of the DMD 80, which region is used.Therefore, in such cases, the location of the axial air separationadjusting section 54 should preferably be altered, such that thedirection of the movement of the sliding section 545 may coincide withthe direction associated with the minimum width of each of the regionsof the formation of the image of the two-dimensional pattern, whichimage is formed on the photosensitive material 150.

When the exposure operation performed in accordance with the imagesignal having been stored in the frame memory of the controllerconnected to the DMD 80 is finished, the GaN type semiconductor lasersLD1 to LD7 are turned off, and the radiating of the laser beams from thelaser beam combining light sources 40, 40, . . . is ceased. Thereafter,the scanning operation performed by the scanner unit 162 for thephotosensitive material 150 in the sub-scanning direction is finished,and the tail end of the photosensitive material 150 is detected by thedetection sensors 164, 164. When the tail end of the photosensitivematerial 150 has thus been detected by the detection sensors 164, 164,the stage 152 is returned by the actuating section (not shown) along theguides 158, 158 to the original position, which is located at the mostupstream side with respect to the scanner support section 160. In caseswhere the next exposure operation is to be performed, the stage 152 isagain moved along the guides 158, 158 from the side more upstream thanthe scanner support section 160 to the side more downstream than thescanner support section 160.

In this embodiment, the microlens array 55 provided with the microlenses55 a, 55 a, . . . for transmitting the light beams La, La, . . . , eachof which corresponds to one of the pixel sections described above andhas passed through the first image forming optical system 51, is locatedwithin the optical system 50. However, the microlens array 55 need notnecessarily be utilized in the optical system 50. With an embodimentwherein the microlens array 55 is not utilized, by the provision of theaxial air separation adjusting section 54, the effects of enabling theadjustment of the focusing point at the time of the projection of thetwo-dimensional pattern of the light onto the photosensitive material150 to be performed easily and quickly are capable of being obtained.

FIG. 17 is a side view showing a different embodiment of the projectingexposure apparatus in accordance with the present invention, wherein anaxial air separation adjusting section is located between a microlensarray and a second image forming optical system, which is an image-sidetelecentric image forming optical system. As illustrated in FIG. 17, ineach of exposure heads 166′, 166′, . . . , an optical system 50′ may beconstituted such that the axial air separation adjusting section 54 maybe located between the microlens array 55 and the second image formingoptical system 52, which is the image-side telecentric image formingoptical system. In this manner, the axial air separation between themicrolens array 55 and the second image forming optical system 52 may bealtered, and the adjustment of the focusing point at the time of theformation of the image of the two-dimensional pattern on thephotosensitive material 150 may thus be performed. With the embodimentof FIG. 17, the same effects as those described above are capable ofbeing obtained. Also, in cases where the optical system 50′ isconstituted as a magnifying optical system, the size of the region fortransmitting the light representing the two-dimensional pattern iscapable of being kept small. Therefore, in cases where the axial airseparation adjusting section 54 is located between the microlens array55 and the second image forming optical system 52, the size of the axialair separation adjusting section 54 is capable of being kept smallerthan in cases where the axial air separation adjusting section 54 islocated between the second image forming optical system 52 and thephotosensitive material 150.

With the projecting exposure apparatus in accordance with the presentinvention, no limitation is imposed upon the wavelengths of the lightused for the exposure operation, and the exposure operation with lighthaving wavelengths falling within various wavelength regions is capableof being performed. Also, no limitation is imposed upon the techniquefor irradiating the light to the spatial light modulation means, thekind of the light source, or the like.

Further, the axial air separation adjusting section is not limited tothe axial air separation adjusting section 54 constituted of thewedge-shaped prism pair 540. For example, the axial air separationadjusting section may be constituted in the manner described below.Specifically, a plane-parallel plate comprising two glass plates and aliquid filled between the two glass plates may be utilized. Theseparation between the two glass plates may be altered by theutilization of a motor, a piezo-electric device, or the like. In thismanner, the axial air separation may be adjusted.

1. A projecting exposure method, comprising: forming a two-dimensionalpattern of light via spatial light modulation, and forming an image ofthe two-dimensional pattern of the light, on a photosensitive material,the two-dimensional pattern of the light being projected onto thephotosensitive material, the photosensitive material being thus exposedto the two-dimensional pattern of the light, and adjusting an axial airseparation in an area upstream of the photosensitive material to adjusta focusing point at the time of the formation of the image of thetwo-dimensional pattern of the light.
 2. A projecting exposure method,comprising: controlling a plurality of pixel sections arrayed intwo-dimensional directions to modulate incident light in accordance witha predetermined control signal forming an image of a two-dimensionalpattern of the light, which has been obtained from controlling theplurality of pixel sections, arraying a plurality of microlenses intwo-dimensional directions, each of which microlenses transmits one oflight beams corresponding respectively to the pixel sections and havingbeen formed into an image formation of the two-dimensional pattern, andforming an image of each of the light beams, which have passed throughthe micro lens array, on a photosensitive material, the two-dimensionalpattern of the light being projected onto the photosensitive material,the photosensitive material being thus exposed to the two-dimensionalpattern of the light, and adjusting an axial air separation in an areaupstream of the photosensitive material to adjust a focusing point atthe time of the formation of the image of the two-dimensional pattern ofthe light onto the photosensitive material.
 3. A projecting exposuremethod, comprising: controlling a plurality of pixel sections arrayed intwo-dimensional directions to modulate incident light in accordance witha predetermined control signal; forming an image of a two-dimensionalpattern of the light, which has been obtained from controlling theplurality of pixel sections, arraying a plurality of microlenses intwo-dimensional directions, each of which microlenses transmits one oflight beams corresponding respectively to the pixel sections having beenformed into an image in the formation of the two-dimensional pattern,forming a second image of each of the light beams, which have passedthrough the microlens array, on a photosensitive material, thetwo-dimensional pattern of the light being projected onto thephotosensitive material, the photosensitive material being thus exposedto the two-dimensional pattern of the light, and adjusting an axial airseparation in an area between the microlens array and forming the secondimage of each light beam to adjust a focusing point at the time of theformation of the image of the two-dimensional pattern of the light.
 4. Amethod as defined in claim 1 wherein adjusting the axial air separationcomprises disposing a wedge-shaped prism pair upstream of thephotosensitive material and moving a position of one of wedge-shapedprisms, which constitute the wedge-shaped prism pair, with respect tothe position of the other wedge-shaped prism and in a direction, whichis associated with a minimum width of each of regions of the formationof the image of the two-dimensional pattern on the photosensitivematerial.
 5. A method as defined in claim 2 wherein adjusting the axialair separation comprises disposing a wedge-shaped prism pair upstream ofthe photosensitive material and moving a position of one of wedge-shapedprisms, which constitute the wedge-shaped prism pair, with respect tothe position of the other wedge-shaped prism and in a direction, whichis associated with a minimum width of each of regions of the formationof the image of the two-dimensional pattern on the photosensitivematerial.
 6. A method as defined in claim 3 wherein adjusting the axialair separation comprises disposing a wedge-shaped prism pair upstream ofthe photosensitive material and moving a position of one of wedge-shapedprisms, which constitute the wedge-shaped prism pair, with respect tothe position of the other wedge-shaped prism and in a direction, whichis associated with a minimum width of each of regions of the formationof the image of the two-dimensional pattern on the photosensitivematerial.
 7. A method as defined in claim 1 wherein the spatial lightmodulation is provided via a digital micromirror device.
 8. A method asdefined in claim 2 wherein the spatial light modulation is provided viaa digital micromirror device.
 9. A method as defined in claim 3 whereinthe spatial light modulation is provided via a digital micromirrordevice.
 10. A method as defined in claim 4 wherein the spatial lightmodulation is provided via a digital micromirror device.
 11. A method asdefined in claim 5 wherein the spatial light modulation is provided viaa digital micromirror device.
 12. A method as defined in claim 6 whereinthe spatial light modulation is provided via a digital micromirrordevice.
 13. A method as defined in claim 7 wherein forming thetwo-dimensional pattern of light comprises using the only a part of theplurality of the pixel sections, which constitute the digitalmicromirror device and are arrayed in the two-dimensional directions.14. A method as defined in claim 8 wherein forming the two-dimensionalpattern of light comprises using the only a part of the plurality of thepixel sections, which constitute the digital micromirror device and arearrayed in the two-dimensional directions.
 15. A method as defined inclaim 9 wherein forming the two-dimensional pattern of light comprisesusing the only a part of the plurality of the pixel sections, whichconstitute the digital micromirror device and are arrayed in thetwo-dimensional directions.
 16. A method as defined in claim 10 whereinforming the two-dimensional pattern of light comprises using the only apart of the plurality of the pixel sections, which constitute thedigital micromirror device and are arrayed in the two-dimensionaldirections.
 17. A method as defined in claim 11 wherein forming thetwo-dimensional pattern of light comprises using the only a part of theplurality of the pixel sections, which constitute the digitalmicromirror device and are arrayed in the two-dimensional directions.18. A method as defined in claim 12 wherein forming the two-dimensionalpattern of light comprises using the only a part of the plurality of thepixel sections, which constitute the digital micromirror device and arearrayed in the two-dimensional directions.
 19. A projecting exposuremethod, comprising: forming a two-dimensional pattern of light viaspatial light modulation, and forming an image of the two-dimensionalpattern of the light, on a photosensitive material, the two-dimensionalpattern of the light being projected onto the photosensitive material,the photosensitive material being thus exposed to the two-dimensionalpattern of the light, and adjusting an axial air separation in an areadownstream of an image forming optical system to adjust a focusing pointat the time of the formation of the image of the two-dimensional patternof the light.